Monday, May 21, 2018

Nipah Virus (NiV) Encephalitis Infection in southern Indian state of Kerala 2018 May

-Dr.M.A.Aleem

Neurologist

Trichy

Tamilnadu

India

In 2018 in the month of May currently there is Nipah virus outbreak in southern India state of Kerala which claims 9 lives .

Till today Tamilnadu is free from Nipah related diseases.

The state

Nipah virus (NiV) infection is a newly emerging zoonosis that causes severe disease in both animals and humans. The natural host of the virus are fruit bats of the Pteropodidae Family, Pteropus genus.

NiV was first identified during an outbreak of disease that took place in Kampung Sungai Nipah, Malaysia in 1998. On this occasion, pigs were the intermediate hosts. However, in subsequent NiV outbreaks, there were no intermediate hosts. In Bangladesh in 2004, humans became infected with NiV as a result of consuming date palm sap that had been contaminated by infected fruit bats. Human-to-human transmission has also been documented, including in a hospital setting in India.

NiV infection in humans has a range of clinical presentations, from asymptomatic infection to acute respiratory syndrome and fatal encephalitis. NiV is also capable of causing disease in pigs and other domestic animals. There is no vaccine for either humans or animals. The primary treatment for human cases is intensive supportive care.

Nipah virus outbreaks in the WHO South-East Asia Region

Nipah virus (NiV) encephalitis is an emerging infectious disease of public health importance in the WHO South-East Asia Region.

Bangladesh and India have reported human cases of Nipah virus encephalitis. Indonesia, Thailand and Timor-Leste have identified antibodies against NiV in the bat population and the source of the virus has been isolated. The status of NiV infection in other SEAR countries is not known although flying bats are found throughout the region.

The first identification of Nipah virus as a cause of an outbreak of encephalitis was reported in 2001 in Meherpur district of Bangladesh. Since then, outbreaks of Nipah virus encephalitis have been reported almost every year in selected districts of Bangladesh.

Repeated outbreaks of Nipah virus encephalitis were established in some districts. Sporadic cases of Nipah virus encephalitis have been reported, mostly from the west and north-western regions of Bangladesh almost every year, with high mortality and constituting a public health threat. Up to March 31, 2012 a total of 209 human cases of NiV infection in Bangladesh were reported; 161 (77%) of them died.

India reported two outbreaks of Nipah virus encephalitis in the eastern state of West Bengal, bordering Bangladesh, in 2001 and 2007. Seventy one cases with 50 deaths (70% of the cases) were reported in two outbreaks.

During January and February 2001, an outbreak of febrile illness with neurological symptoms was observed in Siliguri, West Bengal. Clinical material obtained during the Siliguri outbreak was retrospectively analyzed for evidence of NiV infection. Nipah virus-specific immunoglobulin M (IgM) and IgG antibodies were detected in 9 out of 18 patients. Reverse transcription-polymerase chain reaction (RT-PCR) assays detected RNA from NiV in urine samples from 5 patients.

A second outbreak was reported in 2007 in Nadia district of West Bengal. Thirty cases of fever with acute respiratory distress and/or neurological symptoms were reported and five cases were fatal. All five fatal cases were found to be positive for NiV by RT-PCR.

The morbidity and mortality data of human NiV infection in India and Bangladesh from 2001 to 2012 is presented in Table 1. So far, NiV has infected 263 people and resulting in 196 deaths since 2001. The case fatality rate of Nipah virus encephalitis ranges from 0-100 and average case fatality rate is 74.5%. The case fatality rate has remained high during 2008 – 2012 despite a public awareness campaign and establishment of a referral system for better treatment and nursing care of patients in potential outbreak areas in Bangladesh.

There was no involvement of pigs in NiV transmission as was observed in Malaysia during an outbreak in 1998-99. Consumption of raw date palm sap contaminated by flying bats was the primary source of human NiV infection in Bangladesh.

Nipah cases tend to occur in a cluster or as an outbreak, although 18% of cases in Bangladesh were isolated. Strong evidence indicative of human-to-human transmission of NiV was found in Siliguri (India) in 2001 and in Bangladesh in 2004.

Outbreaks of Nipah in South-East Asia have a strong seasonal pattern and a limited geographical range. The geographical distribution of NiV outbreaks is shown in Fig. 1. All the outbreaks occurred during winter and spring (December-May). This could be associated with several factors like the breeding season of the bats, increased shedding of virus by the bats and the date palm sap harvesting season.

First outbreak of Nipah virus in Malaysia and Singapore
Nipah virus infection was first recognized in a large outbreak of 265 suspected cases in peninsular Malaysia during September 1998 to April 1999. Most patients had contact with sick pigs or had been in close physical contact with Nipah virus infected patients and then presented primarily with encephalitis. The outbreak was initially thought to be due to Japanese encephalitis, but it was later identified as Nipah virus encephalitis.

This outbreak caused widespread panic and fear in Malaysia leading to considerable social disruptions and tremendous economic loss because of the mass culling of over one million pigs. In addition, eleven abattoir workers in Singapore developed a febrile illness caused by Nipah virus during March 1999 following close contact with imported pigs from Malaysia.

The presentation of Nipah virus infection has been variable, ranging from the high mortality observed in the original Malaysian outbreak to an outbreak of low mortality disease among abattoir workers in Singapore, which presented as neurological illness and atypical pneumonia. No new outbreaks have been reported from these countries since May 1999.

In 2018 in the month of May currently there is Nipah virus outbreak in southern India state of Kerala which claims 9 lives . Till today Tamilnadu is free from Nipah related diseases.

The state of Kerala is on high alert after three people from a family have died due to a rare and deadly Nipah viral infection. The deaths were reported in Kozhikode district of northern Kerala.
one of the nurses who treated the deceased also died after showing similar symptoms of illness says an unofficial report.

Fruit Bats: The primary virus carrier
Fruit bats have been identified as the primary carriers of Nipah virus. The virus is usually transferred through fluids from the bat. This happens when humans consume fruits or vegetables which are bitten by infected bats.
Another possibility is that the virus could been transferred to pet animals like cats or dogs who are in direct contact with humans.

Nipah virus infection in humans has a range of clinical presentations, from asymptomatic infection to acute respiratory syndrome and fatal encephalitis.
Nipah virus is also capable of infecting pigs and other domestic animals. There is no vaccine for either humans or animals. The primary treatment for human cases is intensive supportive care.

In india this the third outbreak of Nipha viral diseases in 2018 May at kerala state in southern India.